More than 4,000 staff in Northern Ireland departed under a value-for-money scheme designed to reduce the size of the official payroll, the watchdog concluded.

However, it warned: "Organisations reported that while voluntary exit schemes had led to efficiencies in their operating models they had also led to deterioration in staff morale and a loss of key skills."

While a small number of public bodies noted increased productivity in service delivery and improvements in staff skills and many reported operating efficiencies, others found negative consequences.

More than 10 departments or arm's-length bodies recorded deterioration in staff morale and almost as many lost key skills.

Comptroller and auditor general Kieran Donnelly said: "The Department of Finance managed the implementation of both the Public Sector Transformation Fund and the Northern Ireland Civil Service Voluntary Exit Scheme in a way which was consistent with value for money, within restricted timescales and in an uncertain funding climate."

A total of 4,383 staff were released from the public sector through 23 voluntary schemes in 2015-16, at an estimated cost of £171 million.

Within the Civil Service alone the reduction equated to just over 9% of the total full-time equivalent staff in March 2015.

Redundancies funded in 2015‐16 generated approximate savings of £45 million in 2015‐16, in future climbing to around £155 million annually.

T ight timescales for running staff exits in 2015‐16 precluded the completion of planning to assess priority skills across the public sector, auditors said.

Mr Donnelly added: "Voluntary exit schemes in future years should be based on detailed workforce planning.

"Over time, it will be important to demonstrate that pay bill savings have been sustained and that the schemes have not had a negative impact on staff skills, morale or service delivery."